The objectives of this research are the quantitative determination of the coordination and complexing properties of the trivalent lanthanide cations, and the subsequent application of this information to the study of these ions with ligands of physiological importance. The lanthanides are used extensively as binding agents for interaction site determinations of biological ligands, as probe substituents in metalloenzymes and other systems requiring a metal-ion for activity, as relaxation agents in magnetic resonance imaging, as NMR chemical shift reagents, and as components in numerous industrial processes. The information sought by the proposed experiments includes the maximum coordination number at our conditions of measurement; the determination of variations, if any, of this value through the lanthanide series; the presence of inner-shell complexing and its dependence on anion and solvent properties; the extent of competitive solvation and its dependence on ligand properties; and in all cases, the quantitative determination of the structures of the species in solution. This information will provide a solid framework for the coordination study of four principal deoxyribonucleotides and their component molecules as an initial group of ligands. The experimental techniques to be used permit the direct observation of NMR signals for the components of the primary cation solvation shell, specifically solvent ligands, an ions, and in some systems, the diamagnetic metal-ion itself. In turn, these observations lead to the quantitative evaluation of the lanthanide coordination properties mentioned above. The measurements will be made using a Bruker AM-400 multinuclear, superconducting, Fourier transform NMR spectrometer. Depending on the salt and solvent system, the chemical shift, area, and linewidth techniques to be applied will involve the 1H, 13C, 15N, 31P, 35Cl, 81Br, 127I, and diamagnetic metal-ion nuclei where possible.